cero2k6/plcino

PLCino simulate a simple plc with arduino and python

PLCino simulate a simple PLC with an arduino driving digital (analog not yet) inputs and outputs

PLCino implements the following functions:

• Set functions:

  • def setPLC (nInputs,nOutputs,nMarks,nTimers,nCounts):

    Set the number of inputs, outputs, marks, timers and counters

  • def addMark ():

    Add a new mark and return the position in the array of marks

  • def addTimer():

    Add a new timer and return the position in the array of timers

  • def addCount():

    Add a new counter and return the position in the array of counters

  • def setInputs(newInputs):

    Set the inputs like the given in newInputs with this structure: ";0,1;2,0;3,1;" where ;Number of input, value; Number of input, value; ......

• Contacts:

  • def contact(input, var, imtcq):

    --| |--

    Function contact where var is the number of the imput, mark, timer or counter that activate the contact. imtcq sets the tipe of var value: i(input), m(mark), t(timer), c(counter), q(input)

  • def contactNot(input, var, imtcq):

    --|/|--

    Normaly closed contact

  • def contactPos(input, var, imtcq):

    --|P|--

    Return 1 with a positive flank, 0 in other case.

  • def contactNeg(input, var, imtcq):

    --|N|--

    Return 1 with a negative flank, 0 in other case

• Logic

  • def nott (input):

    -|NOT|-

    Logic NOT

• Coils

  • def coil(input, var, qm):

    --( )--

    Asign the imput to output or mark value. qm sets the tipe of the imput: q (output), m (mark)

  • def coilInv(input, var, qm):

    --(/)--

  • def coilSet(input, var, qm):

    --(S)--

    Set the output or mark value

  • def coilReset(input, var, qm):

    --(R)--

    Reset the coil value

• Timers

  • def ton(input, pt, var):

        ___var_
 input-|   tON|
       |      |
    pt-|______|

ON Timer block. pt = number of seconds. var = number of the timer

• • def toff(input, pt, var):

    OFF Timer block

• Counters

  • def counter(cu, cd, r, pv, var):

          ___var_
       cu-|      |
          |      |
       cd-|      |
          |      |
        r-|      |
          |      |
       pv-|______|

Counter block. CU: increment, CD: decrease, R: reset, PV: target, VAR: counter number

• Comunication:

  • def get():

    Read the input pins state

  • def set(pinstring):

    Write the output pins

Blinked led example

#
#   m0      ___t0__
# --| |-----|   tON|
#           |      |
#         1-|______|
#
#   t0               ___t1__
# --| |--------------|   tON|
#         |          |      |
#         |        1-|______|
#         |
#         |           q0
#         |----------(  )
#
#                     m0
# -------------------( S )
#
#   t1                m0
# --| |--------------( R )
#
####################################################

# Starts the timer 0 with mark 0
ton(contact(1,0,"m"),1,0)

# To do the fork, there are 2 options. This is the first:
# Set the timer with: input = value of timer 0, pt = 1 second, number of this thimer = 1
ton(contact(1,0,"t"),1,1) 
# Set the coil with: input = value of timer 0, number of output/mark = 0, type = output
coil(contact(1,0,"t"),0,"q")

# And this is the second (this is better if you have more logic before the fork):
# aux = contact(1,0,"t")
# ton(aux,1,1)
# coil(aux,0,"q")

# Set the mark with 0 always (input is 1)
coilSet(1,0,"m") 
# Reset the mark 0 when timer1 = 1
coilReset(contact(1,1,"t"),0,"m") 

Notes

• The number of inputs and outputs must be the same in the .py file and .ino file load in arduino
• Serial file (/dev/ttyXXX) must have permissions to read and write
• You can edit the serial config in the 3rd line: ser = serial.Serial('/dev/ttyACM0', 9600)